We present an optical interference model to create chiral microstructures (spirals) and its realization in photoresist using holographic lithography. The model is based on the interference of six equally-spaced circumpolar linear polarized side beams and a circular polarized central beam. The pitch and separation of the spirals can be varied by changing the angle between the side beams and the central beam. The realization of the model is carried out using the 325 nm line of a He-Cd laser and spirals of sub-micron size are fabricated in photoresist.

In this Letter, we introduce a simple metal waveguide array for realizing all-angle wide frequency bandwidth negative refraction from the visible to infrared frequencies. Theoretical analysis from the rigorous coupled-wave theory reveals that the negative coupling constant resulting from the anomalous coupling of guided surface plasmon polariton modes contributes to the negative refraction. The analytical results are confirmed by finite-difference time-domain numerical simulations. Our result provides an alternative way to construct robust all-angle negative refractive materials operating in a wide range of frequency from the near-infrared to the visible range. DOI: 10.1103/PhysRevLett.97.073901 PACS numbers: 42.82.Et, 42.25.ÿp, 73.20.Mf, 78.67.ÿn The negative-refraction (NR) effect [1] has currently attracted considerable interest because it underlays the foundation of a variety of new potential applications [2] and the possibility of investigating extraordinary electromagnetic wave propagation phenomena [3]. It has been demonstrated theoretically and experimentally that both left-handed metamaterials [4 -7] and photonic crystals [8][9][10][11][12][13][14][15] can achieve NR from microwave to near-infrared frequencies. Furthermore, all-angle NR (AANR) for lens imaging at microwave frequencies by metamaterials [16,17] and at optical frequencies by photonic crystals [18,19] has also been demonstrated recently, but the operating bandwidth is still limited in a narrower frequency range [16 -19], and the realization of broadband AANR at an optical frequency, especially in the visible region, is still a challenge.Generally speaking, a periodic structure is capable of producing NR for electromagnetic waves. For example, a simple dielectric waveguide array can bend light in the direction opposite to that observed in common media at a limited incident angle within a narrow frequency bandwidth [20,21]. However, less attention was paid to its metallic counterparts, especially the nanoscale ones [22], until a very recent exploration that nanoscale metal waveguide arrays (MWGAs) show an interesting lens effect at a fixed optical wavelength [23]. In this Letter, we will reveal that nanoscale MWGAs can actually achieve AANR over a wide frequency bandwidth from visible to infrared ranges. We show the NR effect by the coupled-wave theory and further establish the effect by finite-difference timedomain (FDTD) numerical simulations. Further analysis on the conditions for AANR implies that MWGAs are suitable for visible wavelength operation in a wide bandwidth. We attribute the NR effect to coupling of propagating surface plasmon polaritons (SPPs) among the adjacent guides.Our work begins with the analysis of a simple discrete system containing two adjacent two-dimensional (2D) metal waveguides by a rigorous field analysis approach, where linear coupling of propagating SPPs in the guides is considered. The structure is schematically drawn in Fig. 1(a); h is the guide width and d is the thickness of the metal film. " 1 >0 and ...

We have fabricated three-dimensional periodic quasicrystals exhibiting quasiperiodicity of the Penrose structure in the x-y plane and periodic along the z axis using ten-beam visible light holographic lithography. The quasicrystals show photonic band gaps in the visible range. The band gaps are found to follow a simple relation as a function of periodicity and polymeric volume fraction, in accord with the Bragg’s diffraction relation.

We report the use of a (4+1)-beam optical interference holography technique to fabricate woodpile structures in photo-resists. The configuration consists of 4 linearly polarized side beams arranged symmetrically around a circularly polarized central beam with all the beams from the same half space, making it easily accessible experimentally. The fabricated woodpile structures are in good agreement with model simulations. Furthermore, woodpiles with the diamond symmetry are also obtained by exploiting the shrinkage of the photo-resists. Bandgaps in the visible range are also observed for the samples with and without the correct stacking of the woodpile structures.

Abstract:We studied the optical properties of a dielectric photonic crystal structure with spirals arranged in a hexagonal lattice. The dielectric constant of the material is 9 and the filling ratio is 15.2%. We found that this kind of structure exhibits a significant polarization gap for light incident along the axis of the spirals. The eigenmodes inside the polarization gap are right-hand (left-hand) circularly polarized depending on the whether the spirals are left-handed (right-handed). The transmission spectrum of a slab of such a structure has been calculated and matches well with the analysis of the eigenmodes.OCIS codes: (999.9999) photonic bandgap materials. Reference and Links1. See, e.g., I. Tinoco, Jr., M. P. Freeman, "The optical activity of oriented copper helices. I. Experimental", J Phy. Chem. 61, 1196Chem. 61, , (1957. 2. A. Chutinan, and S. Noda, "Spiral three-dimensional photonic-band-gap structure", Phys. Rev. B 57, 2006-2008, (1998) Rev. Lett. 53, 2413Lett. 53, -2416Lett. 53, , (1984. 14. K. Robbie, D. J. Broer, and M. J. Brett, "Chiral nematic order in liquid crystals imposed by an engineered inorganic nanostructure", Nature 399, 764-766, (1999).Spiral is a kind of three-dimensional structure that has chiral character. This kind of structure attracts attention because of its optical activity [1] and its geometric resemblance to the diamond structure [2]. Recent studies by [3,4] also showed that spiral-structured photonic crystals process complete photonic bandgaps and they are also candidates for negative refraction materials [5]. A few innovative techniques have successfully fabricated various forms of spiral structures in the micron and sub-micron scale, and examples including glancing angle deposition (GLAD) [4], two-photon processes [6,7], and holography-lithography [8]. We also find by computer simulations that there are at least two ways to produce a periodic array of separated hollow spiral structures (spring-like structure) by the holographic lithography method. Spring-like spiral structures containing metallic

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The authors studied the thermal radiation properties of a chiral layer-by-layer photonic crystal structure. They found that thermal emissions have a predominantly circular polarization in some frequency ranges and the mechanism underlying this circularly polarized thermal emission is traced to polarization gaps inherent in the layer-by-layer photonic crystal or to surface plasmons if the photonic crystal is supported by a metal substrate.

We report on optically pumped lasing from dye-doped, graded-spacing layer structures of dichromate gelatin emulsions fabricated using two-beam holographic interference. The graded layers exhibited deep and wide photonic band gaps. Multimode lasing with both a low threshold and a high quality factor was observed at the band edge of the photonic band gap. We modeled the emissions from the dye-doped graded layer system using a finite difference time domain technique and achieved good agreement with experimental results. © 2008 American Institute of Physics. ͓DOI: 10.1063/1.2907488͔ Photonic crystals exhibiting band gaps in which electromagnetic wave propagation is not possible have attracted much interest due to the potential that they can manipulate photons in optical microdevices.1 Among the many unique properties of photonic crystals, the control of the photonic density of states has a direct effect on the spontaneous emission of photons, which is an important capability in optoelectronics devices such as lasers, 2 light emitting diodes, 3 microwaveguides, 4 and many other promising photonic devices.5 It has been proposed that the enhancement of the spontaneous emissions in one-dimensional ͑1D͒ photonic crystals doped with gain materials is possible because of the localization at the band gaps and the high density of states at the band edges. 6 The realization of this enhancement was first demonstrated in GaAs light-emitting diodes sandwiched between stacks of 1D Bragg reflectors.7 Since then, lasing from dye-doped polymeric multilayers using distributed feedback and defect modes has been observed. 8,9 Recently, studies on band-edge and defect-mode lasing in dye-doped liquid crystals have attracted interest. 10 In these previous studies, equally spaced layers were employed in the systems. Lasing from 1D layers with gradually changing spacings ͑graded layers͒ is expected to be possible as well.One-dimensional stacks have been fabricated using a time-consuming layer-by-layer spin-coating method.7-9 Holographic lithography that employs the interference of multiple coherent beams is more efficient and has been used to fabricate two-dimensional as well as three-dimensional microstructures in photoresists.11 Furthermore, high-resolution holographic gelatin emulsions can be used to record the interference patterns.12,13 One advantage to using holographic gelatin emulsions is that the structure resulting from the interference is self-supporting inside the gelatin. It was further demonstrated that, with a volume hologram made from dichromate gelatin ͑DCG͒, highly efficient and wide-bandgap 1D layer structures could be achieved.14 The wide-bandgap results from the graded spacing of the 1D layers obtained by the differential swelling of the gelatin during the development process.14 Here, we show that lasing from dyedoped 1D graded layers in DCG holographic emulsions fabricated using two-beam interference is possible. Multimode lasing with both a low threshold and a high quality factor was observed at the band edge of the p...